Pigment composition and process for its production



loose or a compacted condition.

PIGMENT COMPOSITION AND PROCESS FOR ITS PRODUCTION Werner L. Riegler, Western Springs, and Richard L.

Betcher, Chicago, Ill., assignors to Armour and Company, Chicago, 111., a corporation of Illinois No Drawing. Application November 16,1954 Serial No. 469,318

19 Claims. (Cl. 106304) This invention relates to an improved pigment composition and to a process for its manufacture.

Pigments are finely divided insoluble solids which are used in many various materials such as coating compositions, rubber, etc., for many different purposes. In coating compositions they are mostly used to provide,a color or hue; but they also function as opacifiers. In rubber, especially tire rubber, carbon black is used to impart strength and abrasion resistance as well as color. It is hardly possible to look around and not see some article which contains a pigment material.

In practically every application of pigmentary materials it is necessary that they be dispersed, generally in.- a liquid medium. Pigment dispersion, .as it is encountered in the field of coating compositions, involves generally transferring a dry pigmentary material existing really as a heterogeneous dispersion in air to a dispersion in :a liquid as uniform as possible. The attainment of optimum dispersion usually results in the maximum practical development of such desirable properties as tinctorial strength, opacity, gloss and uniform pigment particle distribution.

Pigment particles can be pictured as irregularly shaped solids surrounded by a bound envelope of air, gas or moisture which is to be considered distinctly different in its physical relationship to the pigment as compared with the free air that separates the pigmentparticles. Both the free air and the surface-bound air constitute the initial obstacle to be overcome in converting the pigment from the dispersion in the air to a dispersion in the liquid. Pigments in the dry form are generally in the form of agglomerates which maybe either in a relatively In the dispersionprocess, a vehicle is added to the pigment mass in a mixing operation which is extended further by a so-called grindingoperation. The dispersion processes employed by the manufacturer of coating compositions are not really true grinding operations. They do not reduce, but are intended to approach, the primary particle size of the pigment as originally manufactured. The tendency o'fgthe pigment to cluster or coalesce under the conditions-of packing, shipment and storage, as wellaas -a natural .tendency of many pigments to agglomerate when initial wetting is attempted, are factors which lead one to' be-.

.tamination by abrasion, change in color, quality,;;.- etc.

As a result of the work done on amixture ofpigment ;improved process for transferring pigmentary material from an aqueous system to an oil or resin type system.

and vehicle, a pigmented composition is obtained which 2,852,4M Patented Sept. 16, 1958 may be represented by two extreme conditions, with, of

course, the possibility of an actual composition which combines the characteristics of both. A poor dispersion is one in which the work done has failed to separate the pigment particles with the result that much of the original air is retained and the particles have become tightly packed into a hard aggregate as a consequence of the forces exerted. The ideal result is one in which the pigment particles have been completely separated with an envelope of adsorbed vehicle replacing the original .air envelope, and free vehicle displacing the original free air.

Wetting agents are well known in the field of dispersion, and are employed in emulsification as well as in dispersing solids. Since most pigment manufacturing processes involve the formation of the same at some stage as a precipitate in an aqueous system, it is known to coat the pigment with a wetting agent to render the pigment surface more oil acceptable. However, most filtering the pigment.

We have discovered that if an aqueous precipitate of pigmentary material is treated in such a manner as to ultimately coat the pigment particle with a water-insoluble diacid salt of a N-aliphatic alkylene diamine, the

coating will remain on the pigment during the filtration stepand will act as a spacer between the pigment particles and prevent the formation of clusters of pigment particles or agglomerates. Further, the amount of time required .forgrinding or dispersing these improved pigments into oil or resin type vehicles is considerably diminished, and

there is no adverse etfect upon the properties of the resulting coating compositions.

It is, therefore, an object of the present invention to provide an improved pigment composition.

It is a further object of this invention to provide an improved process for the preparation of pigment materials.

Still another object of this invention is to provide an Further additional objects of this invention will become apparent from the following description.

This invention is applicable, generally, to hydrophilic orwater-wettable pigments and involves treating the pigmentin an aqueous system so as to ultimately coat the pigment particles with a strongly adsorbed Water-insoluble 's alt of a N-aliphatic alkylene diamine. According to a preferred modification of our invention, a small amount of a water-soluble salt of a N-aliphatic alkylene diamine is admixed with a slurry of water-wet pigment material, preferably at a stage in its manufactureprior to drying, and agitated for a time sufficient to adsorb the water-soluble salt onto the surface of the pigment particles, generally about 10 to 15 minutes. Next a stoichiometric quantity of a compoundselected from the group consisting of RCOOZ and R-NH-A-COOZ wherein .R is amaliphaitc hydrocarbon radical having from 12 to 22 carbon atoms, Z is an alkali metal, and A is a divalent aliphatic hydrocarbon radical having from 2 to 3 carbon atoms, is added and the agitation continued whereby a water-insoluble, oil-soluble diacid salt is coated upon the surface of the pigment particles in a quantity ranging from /2 to 4 weight percent, and the alkali metal salt reaction product is dissolved in the aqueous phase.

The coated pigment can then be collected in a filter and dried in an oven at about 95 to 110 C., while the clear filtrate containing the dissolved alkali metal salt is discarded. The coated pigment is now ready for incorporation into an oil or oleoresinous vehicle and will disperse with much less effort than an uncoated pigment.

It will be appreciated that the order of addition of the water-soluble diarnine salt and the alkali metal salt can be reversed. That is, the alkali metal salt or soap can first be admixed with the aqueous pigment system followed by the addition of the water-soluble salt of the diarnine. Our experience has been that the order of addition is not critical. However, it is preferred to add the Water-soluble salt of the diarnine first because of the comparative ease and strength with which it is adsorbed upon the surface of the pigment particles.

Among the diarnine compounds which can be employed according to the present invention are the watersoluble salts, as for example the acetate and hydrochloride, of a N-aliphatic alkylene diarnine having the formula RNH(CH -NH wherein x is an integer of from 2 to 10, and R is an aliphatic hydrocarbon radical having 12 to 22 carbon atoms. R can also represent mixtures of radicals as obtained from tallow, soybean oil, coconut oil, etc. The preferred class of diamines are those in which x is 3, or N-aliphatic trimethylene diamines. The preferred salts are the acetates and the preferred compound is N-tallow trimethylene diamine diacetate.

The anionic compounds which can be used in accordance with the present invention are represented by the general formulas RCOOZ and R-NHACOOZ wherein Z is an alkali metal, A is a divalent aliphatic hydrocarbon radical having 2 to 3 carbon atoms, and R is an aliphatic hydrocarbon radical having from 12 to 22 carbon atoms. R might also represent mixtures of radicals as obtained from tallow, soybean oil, coconut oil, etc. The class of compounds represented by the first general formula are the soaps of long chain fatty acids examples of which include sodium oleate, sodium stearate, sodium palmitate, potassium oleate, etc. The preferred compound of this class is sodium oleate. The class of compounds represented by the second general formula are the alkali metal salts of N-aliphatic aminoaliohatic carboxylic acids. These compounds are formed by the reaction between a long chain amine and an unsaturated acid or ester such as crotonic, acrylic, methacrylic, etc. The preferred compound of this class is sodium N-Cocofl-aminobu'tyrate, formed by the reaction between Coco amine and crotonic acid. For purposes of simplicity, this compound has been designated as A-l300, and will be so referred to in the remainder of the specification and the examples.

As an illustration of the calculations involved in determining quantities of reagents, the reaction between N-tallow trimethylene diamine diacetate and sodium oleate yields approximately 80% of coating material and 20% of sodium acetate as shown by the following reaction.

4 wherein R represents a mixture of radicals as found in tallow and R represents an oleoyl radical. If it was desired to coat lbs. of pigment with 3.0 weight percent of N-tallow trimethylene diarnine dioleate, the amount of reagents added to the pigment water slurry can be determined as follows: The molecular weights of N-tallow trimethylene diarnine diacetate and N-tallow trimethylene dioleate are 440 and 884 respectively. 3% of 100 lbs. requires 3 lbs. of N-tallow trimethylene dioleate, which will require 3.0)(440/884 or 1.49 lbs. of N-tallow trimethylene diarnine diacetate. Since N-tallow trimethylene diamine diacetate is approximately 83% active the corrected quantity of diacetate will amount to 1.79 lbs. The molecular weight of sodium oleate is 304. Since 2 mols of oleate are required to replace the 2 mols of acetate, the quantity of sodium oleate will .be lX3.0 304/884 or 2.03 lbs.

This invention includes the use of the above mentioned chemical agents for treatment of aqueous systems containing all pigments, preferably hydrophilie type pigments, including such materials well known commercially as iron blue, chrome yellow, chrome orange, chrome green, zinc chromate, red lead, azo type toners, aluminum hydrate, lakes, carbon black, iron oxide, zinc oxide, titanium-containing pigments, zinc sulfide-containing pigments, white lead, extenders, etc. Although it is realized that certain of these pigments, such as carbon black are not generally an aqueous mixture ordinarily, it is to be understood that our invention is applicable to such dry pigments when they are brought into an aqueous system. Also within the scope of our invention are the above pigments, as they are ultimately coated according to the process of this invention.

By the term pigment we mean substances which are generally considered insoluble in the vehicle as distinguished from dyestufis which are generally considered soluble. For example, pigments generally have the property of'light refractivity, tending to give opacity to the system, whereas dyes generally only have the property of light absorption, tending to retain the transparency of the system.

The following examples are intended to illustrate the underlying principles of our invention and are not to be construed as unduly limiting.

EXAMPLE I An iron blue pigment, either as a dry stock or a wet press cake, was coated with varying quantities of N- tallow trimethylene diarnine dioleate or N-tallow trimethylene diarnine di-A-l300, according to the preferred process of this invention as hereinabove described. All of the coated pigments along with the uncoated control samples were made into fairly high pigmented roller mill pastes and passed over a laboratory roller mill. A determinan'on was made of grinding time, the number of passes required to produce an enamel grind, and yield value. These pastes were made into paints and checked further for rate of dry indicated by dust free time, tack free time (with Zapon tack tester), color and gloss comparison, and pencil hardness. If the drying time exceeded a the normal 8-hour day, the samples were checked the following morning and were found to be equal. It was found that the coating of the pigments did not impair the final film hardness.

Table I summarizes some of the results of roller mill data obtained while Table II shows the effect of N-tallow trimethylene diarnine dioleate and the corresponding di- A-l300 salt, on heat-cured and air-dried paint enamels.

Table I Per- Coating 1st Pass 2nd Pass cent Per- Material Wetting Aid Gonsist- Total Sample Pigment Vehicle Pigcent Applied From Added in ency of Time Number ment Vehicle Aqueous Solu- Vehicle Por- Paste Grind Grind Grind Grind on Mill By W tion tion N 0. Time, N 0. Time,

Sec. Sec.

1217 Irgl? glue Dry Castor Oll 40 None... B.

0c 121s do do 40 4.0% S. B. 2+

D.T.D O 1219 d0 .do 40 F. 8 1230 Iron 1Blue Press do 40 B. 1 42.6 2 38.9 81. 4

a e. 1231 lrgrti lilue Dry -do 40 60 -do.... 3.0% S. B. 2 37. 6 8 42; 4 79. 9

0c 1232 Inu 1Blue Press ...do 40 60 F. 8 29.2 29.2

a e. 1233 lrg t lilac Dry do 40 60 F. 6 38. 0 8 48.4 86. 4

0C 1234 --do do 40 60 A 0 F. 1 37. 7 7 52. 2 89. 9 1235 luau ame Press -do 40 e0 3.0%A-1aooZII do F. s 31. o 31.0 a e. 1236 Iron Blue Dry Long Oil Alkyd 35 65 None .do 8. B. 1 15.7 3 17.1 32.8

Stock. 52-R-13. 1237 Iron kBlue Press .do 35 65 do S. B. 0 18.8 2 20.8 39.6

a e. 1238 Iron Blue Dry -do 35 65 3.0% S. B. 2 16.6 6 28. 0 34. 1

Stock. D. T. D O 1239 Iron Blue Press do. 35 65 3.0% S. B. 6 20. 2 20. 2

Cake. D. T. D O 1241 Iron Blue Dry -do 35 65 3.0% B. 4 Slips on Rolls Stock. A-1300... 1243, Iron Blue Press .d0 35 65' 2.0% S. B. 5 22.4 8 30,0 52. 4

Cake. D. T. D 0

(1 do 65 3.0% S. B. 8 25. 9 25.9

d 35 65 wi D 0 1? 8 0 8 25. 25.8

I)? T. 1) 35 65 2.0% A4300.-- F. 5 21. 2 8 29. 5 50. 7 85 65 3.0% A-1300 F. 8 26.4 26. 35 65' 4.0%A-1300... F. 8 24. 5 2'4. 5

Mill Setting ca; .005 front roll; .010" rear roll. B.=bodled. S. B.=slightly bodied. F.=fluid. F.= will flow slightly. D. T. D. O.=N-ta1low trimethylene diamine dioleete.

Table II [Humidity-(High) Sample No. (7/28/53) #1243 #1244 #1245 #1246 #1247 #1248 #1236 Percent Coating 2.0% 3.0% 0% None,

D. T. D. 0 D. T. D O D. T. D 0 Blank. Starting Time 8:45 a. m 8:49 a. m 8:55 a. m 9:02 3.1m. Dust Free Time 4:00 p. In 4:00 p. m 4:00 p. In- 4100p. m. Tack Free Time, 125g./5 sec Over-mght Over-night. Over-night Over night. Tack Free Time, l00g./5 sec .do -.do do D Tack Free Time, 200g./5 sec Between Between Between Between 18-24 Hours. 18-24 Hours. 18-24 Hours 18-24 Hours. 18-24 Hours. 24-Hour Pencil Har 48-Hour Pencil Hardness 3B 3B 3B 3B 3B 33. Heat Cured Panels, 1 hour,

275 F Gloss, Good... Gloss, Good... Gloss, Good... Gloss, Good... Gloss, Good... Gloss, Poor; Pencil Hardness 2B 2B 13 2B 2B 1. 2B. Settling Test No Set N No No No Yes. Skinning Some Some 1 Some None None som 1 The use of N-tallow trimethylene diamine dioleate in this formulation of Iron Blue OB-50, andLong-Oil alkyd resin did not prevent skinning,

kmnlng.

while the samples containing the di-A-1300 salt of N-tallow trimethylenediamine showed no signs of s We have found that a paste consisting of 40 parts of iron blue and parts castor oil, when passed over a roller mill once will gel. The addition of more castor oil to the formulation can prevent this, but this is not desirable because an excess will overplasticize the final lacquer film. Samples 1217, 1218 and 1219 in Table I are good examples of how the coating of N-tallow trimethylene diamine dioleate can correct this condition. Referring to the table, it will be seen that sample 1217 bodied so badly on one pass over the roller mill it could not be passed over the mill again. Sample 1218 was prepared with N-tallow trimethylene diamine dioleate added in the vehicle portion of the paste as a wetting aid. This sample made a slightly better dispersion, but most important the paste consistency was sufficiently fluid to "pass over the mill a second time. Sample 1219 is a pigment coated with N-tallow trimcthylcne diamine dioleate from an aqueous solution, which has-lower'edinterfacial tension between pigment and oil to a minimum, leaving a very fluid paint which will disperse easily in one pass over the roller mill to an enamel grind of 7 /2 to 8 (as per Hcgman gauge).

It will be seen from Table I that pigments coated according to the present invention will enable a paint man ufacturer to formulate fluid pastes with high pigment ratios, and further to obtain a decrease in grinding time .as well as to cut down the number of passes formerly required on the roller mill.

The data presented in Table II illustrates that the coating of the pigments according to the present invention has no effects in iron blue pigmented paints on final pen; cil hardness, dust free time, tack free time, color,'.glo'ss, and hiding power. Further, paints that'containeither'of the two coated pigments showed no signs of hard settling,

7 or caking on standing, while the pigments of the control samples formed a hard cake at the bottom of the container.

Chrome green pigments are mixtures of iron blue with a very fine particle size of 0.05 micron, and chrome yellow with a relatively large particle size of 0.3 micron.

cles so coated can no longer act independently of one another, and they will not migrate in the paint film to produce flooding and floating.

EXAMPLE II two samples along with a third control sample Wereformulated into a pigment paste and subsequently into a finished paint composition. Table III lists the dispersion and roller mill data. Table IV summarizes the results of film characteristics.

fications) on the first pass over the mill in 8.2 seconds.

Referring to Table IV, the data illustrates that coating chrome green pigments with N-tallow trimethylene diamine dioleate does not impair gloss, pencil hardness,

color and settling in chrome green paint.

There is some indication in the literature that chrome yellow pigments have a tendency to react with certain organic coating materials at high temperatures, and

thereby cause discoloration of the paint upon baking. Because of this we prepared heat cured panels of the paints containing the coated pigments as well as the control. We found that chrome green pigments coated in accordance with our invention and made into a paint did not show any discoloration on heat curing. Further, our coated pigments produced a paint with a higher gloss, due to a more uniform dispersion.

EXAMPLE III Two samples of iron blue pigments in the form of a water slurry containing 4.28 and 3.1 weight percent solid, respectively, and designated Iron Blue No. 10 and Iron Blue No. 10A, were treated as follows:

Four thousand (4000) parts by weight of sample N0. 10 was divided into two equal parts of 2000 parts by weight each. The control was vacuum filtered and dried at 110 C. for 5 hours and 85.6 parts by weight of dry uncoated iron blue pulverized control was obtained. To the other 2000 parts by weight, 1.42 parts by weight of N-tallow trimethylene diamine diacetate dissolved in hot Table III ROLLER MILL DATA Sample N n #127 #127 #1274.

Pigment Chrome Green Chrome Green Chrome Green. Vehicle 52-R-13 Alkyd- 52-R-13 AikytL- 52-R-13 Alkyd. Pigment: Percent by Wt 65 as 65. Vehicle: Percent by W 35. Coating Material Applied from None Pet. Sulf N-tallow tri- Aqueous Solution. methylene diamine dioleate. Consistency of Paste Med. heavy.-- Heavy. Thin. 1512 Pass on Mill:

Grind N o 3 3 7%. Grind Time, S 7. R 7. 6 8.2. 2nd Pass on Mill:

Grind N n 5 3% Grind Time, Sec 10. 0 9. 0 3rd Pass on Mill:

Grind No 5% 6 Grind Time, Ser' 11. 10.0 Final Grind N 5% R 7%. Total Time Consume 29. 4 26. 6 8.2. Passes Requir '4 1.

Table IV Sample No #1270 #1273 #1274 Heat Cured Panels-1 hour at Gloss Comparativ Poor Goo Good. Pencil Hardness 2B 2B 2 Film 'ihir-lrness 2 2" .002. Color Eq l Settling Test: Separation of Yellow and Blue Pigments Yes, 24 hrs Yes, 24 hrs No. Still Dispersed after 3 months.

Referring to Table III, the control sample No. 1270 had a grind of 3 (as per Hegman gauge) on the first pass over the mill; 5 on the second, and 5 /2 on the third. The total time consumed for all three passes was 29.4 seconds. Sample No. 1273 was treated with 3.0% by weight of petroleum sulfonate' from a water slurry, filtered and dried. This sample passed over the mill in the first pass to produce a grind of 3, 3 /2 on the second pass, and a 6 on the third pass. The total grinding time for this sample was 26.6 seconds. Sample No. 1274 coated with 3.0% by weight of N-tallow trimethylene diamine dioleate, reached a grind of 7 /2 (enamel speciwater was added and mixed for 15 minutes. To this 1.84 parts of sodium oleate dissolved in hot water was added and agitated for about 15 minutes. The resulting slurry was vacuum filtered and dried at C. for 5 hours. 85.6

parts by weight of pulverized 3% N-tallow trimethylene Table V DISPERSION DATA FOR IRON BLUE #10 [3 Roll MilL] Sample N o. #10 Control #10 Coated Vehicle Used Vehicle by Wt Pigment by Wt Relative Viscosity grins go 2nd Pass: 3 1 20 6 g gg gp 1 line 1 15.9 Roll Setting: 1 17 7 Back .015 l b f on Absorption 51.0-- 41.0. Total Time Consumed on Mill 2' 58.9 2 '38A.

Table VI ROLLER MILL DATA FOR IRON BLUE #lOA' Sample No #lOA Control #101 Coated Vehicle Used Linseed Linseed V glehicle tbg Vat? 60 p a r f gmen y Relative Viscosity 40 parts 1st Pass:

0. 1 02.8; Grilng go 2.

r line 1 05.7 1 00.6" 1 3rd Pass: Grind No 4 5. Roll Setting:

Front .001" .001".

Back .016 .015. Total Time Consumed on Mill 3 59.7 2 03.4". Oil Absorptirm 75,4 64,5,

Results of iron blue samples No. 10 and 10A coated pigments show a better dispersion and a decrease in the time consumed on the mill when compared to the uncoated controls. The actual'time saving is much more pronounced on a large production basis. Assuming that it is expected to obtain an enamel grind of 6 with this blue pigment, it would be necessary to pass an uncoated pigment paste twice over a 5 roll mill. On the other hand, it'would be possible to obtain a grind of 6 with one pass of a pigment coated in accordance with our invention. Therefore, the paint manufacturer can actually enjoy better than a 50% saving of time.

While this invention has been described and exemplified in terms of its preferred modification, it will be readily appreciated that many modifications and variations may be made without departing from the spirit and scope of the invention.

We claim:

1. A pigment particle uniformly coated with from V2 to 4 weight percent of a water-insoluble, oil soluble diacid salt of a N-aliphatic alkylene diamine, said diamine having the general formula RNH(CI-I NH and said acid is selected from the group consisting of RCOOH and RNHA-COOH wherein R in each formula is an aliphatic hydrocarbon radical having from 12 to 22 carbon atoms, x is an integer of from 2 to 10, and A is a divalent aliphatic hydrocarbon radical having from 2 to 3 carbon atoms.

2. A pigment particle uniformly coated with from /2 to 4 weight percent of a water-insoluble, oil soluble diacid salt of a N-aliphatic trimethylene diamine having the general formula RNHCH CH CH NH and said acid is selected from the group consisting of RCOOH and RNH-A-COOH wherein R in each formula is an aliphatic hydrocarbon radical having from 12 to 22 10% carbon-atoms and A isa divalent aliphatic hydrocarbon radical *having from 2 to '3 carbon atoms.

3.'A- pigment particle uniformly coated with from h to '4 weight percent of'a water-insoluble, oil soluble diacid salt of a -N-aliphatic trimethylene diamine, said diamine having the general formula R-NH-CH CH CH -NH and said acid having the formula RCOOH wherein R in-each'formula is an aliphatic hydrocarbon radical-having-from'12 to 22 carbon atoms.

4. A pigment particle uniformly coated with from b to 4 weight percent of a water-insoluble, oil-soluble'diacid salt of a N-aliphatic trimethylene diamine, said diamine having the general formula said acidhaving the formula RNHACOOH Where'- in Kin-each formula is an aliphatic hydrocarbon radical having from 12 to 22 carbon atoms, and A is a divalent aliphatic hydrocarbon radical having from 2 to" 3 carbon atoms.

5. A pigment particle uniformly coated with from /2 to- 4*weight percent of N-tallow trimethylene'diamine diolea'te.

6. A 'pigment particle uniformly coated with from /2 to'4 weight percent of N-tallow trimethylene diamine -di- N-Coco-aminobutyrate.

7. At pigment particle uniformly coated with from /i'to 4'weight percent of N-sdya trimethylene diamine dioleata' 8. A pigment particle uniformly coated with'f'rorn /2 to 4 weight percent of NCoco trimethylene diamine dioleate.

9; A process comprising separately addingwith-agitation to 'an'aqueous pigment system stoichiometric quanti tiesof' (A) a water-soluble salt of a N'-aliphatic alkylene diamine ofthe formula R -NH-(CH -NH and.(B) a compoundselected from the group consistingof' compounds having the formulas RCOOZ and R-NH-A-COOZ wherein R in each of the foregoing formulas'is an aliphatic hydrocarbon radical having from 12 to 22 carbon atoms, x is an integer of from 2 to 10, Z is an alkali metal, and A is an aliphatic hydrocarbon radical having from 2 to 3 carbon atoms, to produce on the pigment particles a uniform coating constituting /2 t0 4 weight percent of a water-insoluble, oil soluble diacid salt of a N aliphatic alkylene diamine and an aqueous phase containing a dissolved alkali metal salt reaction product; and separating'the' thus-coated pigment from" the aqueous hase. p 10. A process comprising separately adding with agitation to an aqueous pigment system stoichiomet-ric quantities of (A) a Water-soluble salt of a N-aliphatic trimethylene diamine of the formula R--NHCH CH CH NH and (B) a compound selected from the group consisting of RCOOZ and RNHACOOZ wherein R in each of the foregoing formulas is an aliphatic hydrocarbon radical having from 12 to 22 carbon atoms, Z is an alkali metal, and A is a divalent aliphatic hydrocarbon radical having from 2 to 3 carbon atoms, to produce on the pigment particles a uniform coating constituting /2 to 4 weight percent of a Water-insoluble, oil-soluble diacid salt of a N-aliphatic trimethylene diamine and an aque ous phase containing a dissolved alkali metal salt reaction product; and separating the thus-coated pigment from the aqueous phase.

11. A process comprising separately adding with agitation to an aqueous pigment system stoichiometric quantitles of (A) a water-soluble salt of a N-aliphatic trimethylene diamine of the formula and (B) a compound of the formula RCOOZ wherein R in each of the foregoing formulas is an aliphatic hydrocarbon radical having from 12 to 22 carbon atoms and Z is an alkali metal, to produce on the pigment particle a uniform coating constituting V2 to 4 weight percent of a water-insoluble, oil-soluble diacid salt of a N-aliphatic trimethylene diamine and an aqueous phase containing a dissolved alkali metal salt reaction product; and separating the thus-coated pigment from the aqueous phase.

12. A process comprising separately adding with agitation to an aqueous pigment system stoichiometric quantities of (A) a water-soluble salt of a N-aliphatic trimethylene diamine of the formula and (B) a compound of the formula RNHACOOZ wherein R in each of the foregoing formulas is an aliphatic hydrocarbon radical having from 12 to 22 carbon atoms and A is a divalent aliphatic hydrocarbon radical having from 2 to 3 carbon atoms and Z is an alkali metal, to produce on the pigment particles the uniform coating constituting /2 to 4 weight percent of a waterinsoluble, oil-soluble diacid salt of a N-aliphatic trimethylene diamine and an aqueous phase containing a dissolved alkali salt reaction product; and separating the thus-coated pigment from the aqueous phase.

13. A process comprising separately adding with agitation to an aqueous pigment system stoichiometric quantities of (A) a diacetate salt of a N-aliphatic trimethylene diamine of the formula and (B) an alkali metal oleate wherein R is an aliphatic hydrocarbon radical having from 12 to 22 carbon atoms, to produce on the pigment particles a uniform coating constituting to 4 weight peroent of a N-aliphatic trimethylene diamine dioleate and an aqueous phase containing dissolved alkali metal acetate; and separating the thus-coated pigment from the aqueous phase.

14. A process comprising separately adding with agitation to an aqueous pigment system stoichiometric quantities of (A) a diacetate salt of a N-aliphatic trimethyl ene diamine of the formula.

R NH-canon,CH -NH wherein R is an aliphatic hydrocarbon radical having from 12 to 22 carbon atoms and (B) an alkali metal N-Coco-aminobutyrate to produce on the pigment particels a uniform coating constituting ,6 to 4 weight percent of N-aliphatic trimethylene diamine di-alkali metal- 12 N-Coco-aminobutyrate and an aqueous phase containing dissolved alkali metal acetate; and separating the thuscoated pigment from the aqueous phase.

15. A process comprising separately adding with agitation to an aqueous pigment system in stoichiometric amounts (A) N-tallow trimethylene diamine diacetate and (B) sodium oleate to produce on the pigment particels a uniform coating constituting /2 to 4 weight percent of N-tallow trimethylene diamine dioleate and an aqueous phase containing dissolved sodium acetate; and separating the thus-coated pigment from the aqueous phase.

16. A process according to claim 9 wherein the watersoluble salt of the N-aliphatic alkylene diamine is added prior to the alkali metal compound.

17. A process according to claim 9 wherein the alkali metal compound is added prior to the water-soluble salt of the N-aliphatic alkylene diamine.

18. A process which comprises first adding with agitation to an aqueous iron blue pigment system a quantity of N-tallow trimethylene diamine diacetate; secondly, adding a stoichiometric quantity of sodium oleate to produce on the pigment particles a uniform coating constituting /2 to 4 weight percent of N-tallow trimethylene diamine dioleate and an aqueous phase containing dissolved sodium acetate; separating the thus-coated pigment from the aqueous phase and drying it at a temperature in the range of to C.

19. A process comprising separately adding with agitation to an aqueous iron blue pigment system a quantity of N-tallow trimethylene diamine diacetate; secondly, adding a stoichiometric quantity of sodium N-Cocoaminobutyrate to produce on the pigment particles a uniform coating constituting /2 to 4 weight percent of N-tallow trimethylene diamine di-sodium-N-Coco-aminobutyrate and'an aqueous phase containing dissolved sodium acetate; separating the thus-coated pigment from the aqueous phase and drying same at a temperature in the range of 90 to 110 C.

References Cited in the file of this patent UNlIED STATES PATENTS 2,126,925 Ryan et a1 Aug. 16, 1938 2,192,956 Sloan et al Mar. 12, 1940 2,442,972 Edelstein Jan. 8, 1948 2,709,160 Korejwa et a1 May 24, 1955 2,728,682 Kalenowiski et a1 Dec. 27, 1955 2,728,737 Witcofl? Dec. 27, 1955 2,736,658 Pfohl Feb. 28, 1956 

1. A PIGMENT PARTICLE UNIFORMLY COATED WITH FROM 1/2 TO 4 WEIGHT PERCENT OF A WATER-INSOLUBLE, OIL SOLUBLE DIACID SALT OF A N-ALIPHATIC ALKYLENE DIAMINE, SAID DIAMINE HAVING THE GENERAL FORMULA R-NH-(CH2)X-NH2 AND SAID ACID IS SELECTED FROM THE GROUP CONSISTING OF RCOOH AND R-NH-A-COOH WHEREIN R IN EACH FORMULA IS AN ALIPHATIC HYDROCARBON RADICAL HAVING FROM 12 TO 22 CARBON ATOMS, X IS AN INTEGER OF FROM 2 TO 10, AND A IS A DIVALENT ALIPHATIC HYDROCARBON RADICAL HAVING FROM 2 TO 3 CARBON ATOMS. 